A number of architectures of inverters of this type are already known, for example diode-clamped inverters. Document FR-A-2 437 102 describes an inverter of the neutral point clamped type designated by the English acronym NPC, which corresponds to the above definition and in which diodes connected to a middle point between two consecutive generators, called the reference point, serve to distribute the input voltage between the transistors in the blocked state of the two first commutation branches.
The output current and voltage of such an architecture are rich in harmonics, requiring the use of filter means, which presents problems for variable-speed applications such as use with motors, for example. The addition of supplementary levels relative to a three-level NPC-type inverter allows the voltage harmonics generated by the converter to be reduced, thus enabling the associated sinus filter to be reduced in size or even eliminated altogether. However, the change from a three-level NPC-type inverter to a five-level NPC-type inverter, for example, requires the use of an additional four IGBT transistors and twelve diodes, which increases the costs considerably.